Active and retained states for locks
When a lock is first acquired, it is an active lock. It remains an active lock until successful completion of the unit of work, until it is released, or until it is converted into a retained lock if the unit of work fails or for a CICS® or SMSVSAM failure.
CICS® supports active and retained states for locks.
- If a unit of work fails, RLS VSAM or the CICS® enqueue domain continues to hold the record locks that were owned by the failed unit of work for recoverable data sets, but converted into retained locks. Retaining locks ensures that data integrity for those records is maintained until the unit of work is completed.
- If a CICS® region fails, locks are converted into retained locks to ensure that data integrity is maintained while CICS® is being restarted.
- If an SMSVSAM server fails, locks are converted into retained locks, with the conversion being carried out by the other servers in the sysplex, or by the first server to restart if all servers have failed. This means that a unit of work (UOW) that held active RLS locks holds retained RLS locks following the failure of an SMSVSAM server.
Converting active locks into retained locks not only protects data integrity. It also ensures that new requests for locks owned by the failed unit of work do not wait, but instead are rejected with the LOCKED response.